Visible or invisible reference lines are projected in many applications, said reference lines serving as a reference for either the human eye or for electronic systems and also allowing automatic positioning or machine guidance. Here the reference lines are usually created by widening a laser beam, which is possible for straight lines in particular, or else by rotating projection of a laser point.
An example of technical devices suitable for this are rotating lasers, which serve to fix a plane using a visible or invisible laser beam and have been in use for a number of years now, for example in the building trade or in industry. They are a valuable aid for marking construction lines on horizontal, vertical or else defined angled planes. However, previous rotating lasers are disadvantageous in that they are only able to create those projection planes which contain the initial point of the laser beam. Thus, in order to project spatial points along a line in a predefined horizontal plane, the light emission point of a conventional rotating laser must be positioned precisely in this plane and the laser module must be adjusted precisely to the horizontal light emission (and the rotation axis must be aligned precisely vertical). Thus, the work region for using a rotating laser for marking a horizontal plane is restricted to the adjustment region for the height of a base on which the rotating laser is mounted. Projecting a laser beam rotating about a vertical axis by means of a conventional rotating laser in a non-horizontal (e.g. directed obliquely upward) direction leads to spatial points situated closer being projected to a lower height than spatial points situated further away.
WO 96/18083 describes a method and a device for measuring and marking on distant lines, areas or in at least partly enclosed spaces. One or more relevant spatial points are measured according to in each case two spatial angles and the distance from a reference point by means of a gimbal-mounted laser rangefinder. The laser rangefinder can be pivoted about two mutually perpendicular axes, which are equipped with goniometers. According to one embodiment described in this document, spatial points to be measured are targeted manually, and marking points are calculated from the measurement data on the basis of a predetermined relative relation between measurement and marking, which marking points are then autonomously targeted by the measuring and marking device.
An embodiment for carrying out absolute measurements and markings is also disclosed, for the purposes of which system leveling is carried out, which places the mathematical model for calculating the spatial point coordinates in relation to the actual directions in space, as a result of which it is also possible, for example, to drop perpendiculars in space.
However, no automatically running functionality is disclosed, by means of which spatial points lying in a common horizontal plane, which does not contain the emission point of the laser beam, could be targeted and marked in a simple manner; nor is an automatic sequential measurement of a plurality of spatial points extending on an iso-contour line disclosed, for comparison with for example a scan.
U.S. Pat. No. 6,547,397 discloses a laser projection system for projecting a three-dimensional image onto an object and a corresponding projection method, wherein a coordinate system is fixed by selecting at least three reference points on the object, a laser beam is projected onto each of these reference points, and the distance from each of the reference points is established by determining the propagation time of the laser beam and the horizontal and vertical angles to the object, and therefrom the three-dimensional orientation of the laser projector relative to the object is established. Although a three-dimensional object measurement or a corresponding object projection is possible on the basis of this disclosure, this document provides no indications in respect of a functionality by means of which spatial points could easily be generated in a horizontal plane which does not contain the emission point of the laser beam.
EP 1 733 185 discloses a device and a method, by means of which edges in particular are to be measured precisely on a polygonal, but otherwise planar surface. This document also does not provide indications in respect of a functionality by means of which spatial points could easily be generated in a horizontal plane which does not contain the emission point of the laser beam. Nor are there any indications in respect of measuring or projecting spatial points on arbitrary, non-polygonal surfaces.
EP 2 053 353 discloses a reference line projecting device with an electro-optical rangefinder. According to the teaching of this application, an optical reference beam, more particularly a laser beam, is guided along a defined reference path. In conjunction with running through the reference path, there is a distance measurement with respect to at least one point of the reference path by emitting a measurement beam which is parallel to or coaxial with the reference beam or by using the reference beam as measurement beam. After receiving portions of the backscattered measurement beam, a signal is derived from these portions and a distance to the at least one point is determined from the signal, wherein the guiding along the reference path is repeated at least once and a distance or distance-related variable is established in each case for the at least one point every time the reference path is run through. Thus, in the case of angle-synchronous distance measurements, the same points are scanned a number of times.
By integrating a rangefinder, the system disclosed in EP 2 053 353 also enables control of the projection on the basis of an established surface topography. In particular, what is disclosed is that, after determining a surface profile, a projection can be adapted to a curved surface in such a way that distortions as a result of the curved surface are compensated for and the projection corresponds to the undistorted contour of an object to be measured or marked.
However, nor does EP 2 053 353 disclose or suggest a functionality by means of which spatial points could easily be generated in a horizontal plane which does not contain the emission point of the laser beam.